Just how much will my truck tow in the shape it's in?

Truck's towing capacity is roughly 7400 lb but I have to
move to Ohio from Virginia which is roughly 800 MI with the
trailer that is going to become my mobile home and as it
sits empty right now it's 7000 or 7500 lb and by the time I'm
done with it I'm likely to add about two to three more
thousand pounds to the weight of it my worry and question
is whether or not my pickup will make it there it has
173,000 mi on it already so it's no new truck a 99 Dodge
ram 1500  idk if it's ST or WS model 5.2 l V8. But it had 123,
000 mi on it 2 years ago when I bought it and I've done a lot
of scrapping in it so it's had full payload and I've exceeded
it multiple times. Actually even better put it's basically
always at full payload capacity which I know does put wear
and tear in the motor and because of that you do hear a
slight knock in the motor when you're driving and you go to
accelerate pass 40 mph and if you try and do it fast and
knocks hard so I need some suggestions